The present invention relates generally to valves and more particularly, to valve configurations that are suitable for intravenous (IV) administration set applications while readily lending themselves to mechanized activation.
The control of fluid flow through an IV administration line from a fluid source to a patient is of primary concern in infusion systems. In many cases, infusion devices such as pumps or controllers are used with the IV administration set in the infusion of medical solutions to patients. These devices typically include a means which continually occludes the IV tubing to prevent free flow, although the position of occlusion may move during operation. For example, in the case where a peristaltic mechanism of some type is used, the mechanism creates a moving zone of occlusion to move the fluid at a controlled rate from the fluid source to the patient. The tubing is always occluded at one position or another. Other types of infusion devices may use valves to sequentially occlude the tubing. Thus, while the tubing of the administration set is engaged with the infusion device, most, if not all, infusion devices occlude the tubing thereby preventing free flow of the supply fluid to the patient. However, before and after the tubing is engaged with the infusion device, free flow of the IV fluid is possible and is a concern.
A large variety of valve mechanisms and valve configurations have been devised to fulfill a variety of different requirements. The requirements specific to IV set applications include low cost, as such devices are typically intended to be disposable, and ease of manipulation, preferably such that the valve can readily be actuated by a simple automated mechanism as well as manually. Many devices utilized in IV set-type applications have either been of simple, consequently inexpensive design and rather awkward to manipulate or alternatively, relatively easy to actuate but inordinately complex and therefore expensive.
An example of the former is a pinch clamp that is fastened about the exterior of resilient tubing. Opposing surfaces are brought to bear against the tubing's exterior to pinch its walls shut to prevent flow while two adjoining, appropriately configured surfaces cooperate to function as a ratchet mechanism in order to maintain the clamp in a closed or partially closed position. Squeezing the two opposing surfaces together shuts off flow while separating the two adjoining surfaces permits flow. Although such a device is of one-piece construction, two very different movements are required to open and to close the valve thereby rendering the valve rather difficult to adapt to a simple automated actuation mechanism.
An example of a device that requires a relatively simple movement to actuate is that disclosed in U.S. Pat. No. 3,971,541 to Griffin. A pulling action on a pull ring causes the valve to open while release thereof allows the valve to automatically return to its closed position. However, the valve employs numerous parts including a plunger, sealing plug, two biasing means, O-rings, etc. thereby resulting in a rather expensive unit.
The valve provided by Cloyd, U.S. Pat. No. 3,806,086 relies on fewer parts than does the Griffin valve but actuation calls for somewhat more complex movement, requiring the insertion of a supply line thereinto in order to depress a stem element which serves to open a flow path. Removal of the supply line allows a spring to urge the stem back into its closed position thereby preventing flow. While this mechanism is very simple to actuate manually, it appears rather ill-suited for mechanical manipulation. In addition, no less than four parts are incorporated in the design.
In the prior art, manually actuated flow stop clamps have been used to prevent free flow during periods when the administration set is not engaged with the infusion device. However, operation of the manually actuated clamp requires further responsibility on the part of the operator to assure that the clamp is in the correct position. For example, before engagement with the infusion device, the operator must assure that the clamp is closed to prevent flow. After engagement with the infusion device, the operator must assure that the clamp is open to permit flow so that the infusion device can move the fluid to the patient. And, before removal of the tubing from the infusion device, the operator must once again assure that the clamp is closed to prevent flow. A system which automatically performs the above operations would be preferable.
Additionally, a flow control device which indicates its current operational status to the operator is desirable. For example, a positive click indicating that the valve has been placed in the open or "flow" position and a positive click indicating the valve has been place in the closed or "flow stop" position are desirable. Some degree of confidence is then instilled in the operator that the flow control device is actually in the desired configuration.
Hence, those concerned with infusion systems have recognized that it would be of value to provide an automated system which would prevent free flow through an IV administration set connected between a fluid supply and a patient during times when the administration set is not engaged with an infusion device, which will permit flow when the administration set is engaged with the infusion device and which will simplify the infusion procedure. Additionally, it has been recognized that it would be of value to provide a flow control valve which is relatively easy and inexpensive to manufacture and which clearly indicates to the user its operational configuration. The present invention fulfills these needs.